Finding the Right Shrub for a Retaining Wall in Philadelphia

You need a compact, rounded perennial or shrub about 18 inches tall and wide for a sunny, well-drained spot atop a 2-foot retaining wall with only 1 foot of soil. Since the site has good drainage but limited soil depth, choose plants with fibrous roots that tolerate dry conditions.

Excellent Candidates for Your Wall Top

• Dwarf Korean Lilac (Syringa meyeri 'Palibin'): 4-5 ft but can be kept smaller; fragrant spring flowers; full sun.
• Blue Star Juniper (Juniperus squamata 'Blue Star'): Slow-growing, 2-3 ft tall/wide; steel-blue foliage; drought-tolerant.
• Dwarf Fothergilla (Fothergilla gardenii 'Mount Airy'): 2-3 ft; white bottlebrush flowers, great fall color; part shade to sun.
• Creeping Phlox (Phlox subulata): 4-6 inches tall, spreads 2 ft; spring flowers; evergreen foliage; full sun.
• Sedum 'Autumn Joy' (Hylotelephium): 18-24 inches; succulent leaves, late summer flowers; thrives in shallow, dry soil.
• Dwarf Boxwood (Buxus microphylla 'Green Velvet'): 2-3 ft; dense, evergreen; shear to shape; part shade.

Next Steps

Assess the exact sun exposure (hours of direct sun), wind exposure, and whether irrigation reaches the spot. Take photos of plants you like around the neighborhood for identification. With that info, a local nursery can pinpoint the best match.